Edit and Simulate the Program on CNC Machines

Once the part program is entered in the machine and execution command is given for producing the part, the operator has no control over machine movements except minor modifications such as overriding spindle RPM and feed. In case of any undesired movement of the tool, the machine can only be stopped through the emergency stop switch or the “reset” button. Any carelessness may result in serious damage to the machine. So, the program must be thoroughly verified before executing it on the machine for production. CNC machines come with suitable simulation softwares (both on-line and off-line). Such software simulates the tool movement on a graphic screen. It is possible to select any tool from its tool library which contains numerous types of tools. Some software provides the facility for user defined tools also.

The software first checks the program syntax. Any error is pointed out. Help files are provided to pin-point the error, suggesting suitable remedial action. When the program is found okay syntax-wise, the simulation starts. In simulation, the billet of given dimensions is shown on the screen and the chosen tool starts moving with respect to it as per tool movements provided in the program. When the tool passes over the shaded representation of the billet, that part of the billet is erased, simulating the machining operation. This is repeated for all the tools used in the program. The resulting shape, obtained after the end of the program, represents the final shape of the machined job.

All the time during simulation, the coordinates of the tool tip are displayed on the screen. It is also possible to see the simulation in steps, i.e., block-by-block. This way it becomes very easy to verify the desired tool path. The tools move exactly in the same manner during the actual machining operation. So, if the simulation is found correct, one can be sure that there will be no undesired movement of the tool on the machine and the desired part will be produced.

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